Differential gear

A differential gear that distributes a driving force for a vehicle to a first output shaft and a second output shaft, the differential gear comprising:

• a cylindrical first connecting member including, on an inner periphery of the first connecting member, a plurality of straight-spline protrusions to which the first output shaft is coupled by straight splines;
• a cylindrical second connecting member including, on an inner periphery of the second connecting member, a plurality of straight-spline protrusions to which the second output shaft is coupled by straight splines;
• a first side gear combined with the first connecting member;
• a second side gear combined with the second connecting member;
• a plurality of pinion gear sets each composed of a first pinion gear and a second pinion gear being meshed with each other, the first pinion gear meshing with the first side gear, and the second pinion gear meshing with the second side gear;
• a differential case that holds the plurality of pinion gear sets;
• and
• a center washer that is disposed between the first side gear and the second side gear, rotation of the center washer relative to the differential case being restricted, wherein
• the first side gear is formed with:
• a first cylindrical portion disposed around an outer periphery of the first connecting member and coupled to the first connecting member by helical splines;
• and a first wall portion extending radially inward from one end on the center washer side of the first cylindrical portion, the first wall portion protruding radially inward beyond the plurality of straight-spline protrusions of the first connecting member,
• the second side gear is formed with:
• a second cylindrical portion disposed around an outer periphery of the second connecting member and coupled to the second connecting member by helical splines;
• and a second wall portion extending radially inward from one end on the center washer side of the second cylindrical portion, the second wall portion protruding radially inward beyond the plurality of straight-spline protrusions of the second connecting member, and
• during driving in which torque is transferred from the first side gear and the second side gear to the first connecting member and the second connecting member, the center washer generates a frictional force between the center washer and each of the first wall portion of the first side gear and the second wall portion of the second side gear by a thrust force generated by coupling by the helical splines.